The present invention relates to a novel process for making benzophenone.
There are many known methods of manufacturing benzophenone. The best known method is the Fiedel-Crafts reaction. In this method aluminum chloride, benzene and carbon tetrachloride are reacted to form the intermediate dichlorophenylmethane which, upon hydrolysis, gives benzophenone. Benzophenone has also been made by a Friedel-Crafts reaction which involves condensation of benzene and phosgene in the presence of aluminum chloride. (German Pat. No. 403,507). The manufacture of benzophenone by condensation of benzene with benzoyl chloride by a noncatalytic or thermal process has been disclosed in U.S. Pat. No. 2,528,789. Benzophenone is also obtained from o-benzoylbenzoic acid by decarboxylation using a fluid-bed catalyst (Italian Pat. No. 542,862), and by decarboxylation in an inert heat-stable medium using a catalyst (French Pat. No. 994,850). A number of other methods are disclosed by patents. These patents disclose the oxidation of diphenylmethane with nitric acid (Swedish Pat. No. 137,686), oxidation of benzhydrol or diphenylmethane with chromic acid (U.S. Pat. No. 2,794,813) and oxidation of diphenylmethane with oxygen or air in the presence of a metal salt catalyst (U.S. Pat. No. 2,859,247).
Although the various techniques described in these patents are capable of producing benzophenone, they are each disadvantageous for various different reasons.
Accordingly, it is an object of the present invention to provide a new process for producing benzophenone which can be carried out in a simple and straight-forward manner to yield benzophenone in significant yields.